Problem: Simplify the following expression: $a = \dfrac{4}{2q} + \dfrac{-2}{2q}$
Answer: Since the expressions have the same denominator we simply combine the numerators: $a = \dfrac{4 - 2}{2q}$ Combine like terms: $a = \dfrac{2}{2q}$ Simplify by dividing numerator and denominator by 2: $a = \dfrac{1}{q}$